The present invention relates to a method of managing the storage in a memory of a picture processing system, the said memory of the dynamic type being organised in rows and columns with burst-type access, in which system the pictures are processed blockwise, each block being square or rectangular and comprising a plurality of pixels (H*V) in the horizontal and the vertical direction, and the description of the pixels within a block being effected by considering the pixels one after the other in consecutive parallel lines in the block.
It also relates to an arrangement provided with a memory of the dynamic type, organised in rows and columns with burst-type access, for storing a blockwise processed picture, each one of the said blocks being a square or a rectangle whose horizontal and vertical dimensions, expressed in a number of pixels which are integral powers of two, the description of the pixels contained in a block being effected by considering the pixels in consecutive parallel lines of the block.
For the low-rate information component picture compression algorithms, the temporal processing is of great importance, requiring a considerable storage capacity. Moreover, for this type of algorithm, the number of pixels to be processed per unit of time is fixed, which is done, on the one hand, to prevent degradation of the performances of the algorithms and on the other hand to set a limit to the complexity of the encoding and decoding systems. A direct consequence is that the number of pixels to be encoded in a picture and consequently the number of words necessary for its storage is limited.
In certain picture compression applications in which it is desirable to use a variable picture format (form factor), it is neccessary to find an adequacy between the variable format of the pictures and the fixed dimension of the memory intended to receive the pictures during the decoding procedure. Such a case occurs in a multimedia application such as the Interactive Compact Disk ("CDI"), where the picture format is variable.
One of the critical points in the realization of compressed picture decoders based on blocks is the fact that a large quantity of addresses is necessary to access the memory. The memories usually employed for reasons of cost and integration are dynamic memories which are characterized by an access in two time periods consisting in the supply in a first time period of the "row" address and thereafter, after a delay which depends on the type of memory used, the supply in a second time period of the "column" address, and finally the access to the information after a further delay. The access can be faster when the information components to be read are situated in the same row or in consecutive "column" addresses, by utilizing a mode designated "static column mode" or "page mode". In these two cases, the access to the first information corresponds to the two time periods described in the foregoing, but the access to the subsequent information components only requires the second time period.
A further disadvantage is the poor efficiency in the use of the memory location when the number of pixels per line or the number of lines per picture is not a multiple or a submultiple of the number of colums or number of rows of the memory sections.
The document EP-A-0 085 210 describes the use of a specific addressing mode with address jumps in the memory for consecutive picture lines, with the object of facilitating the search for clusters of particular elements. But said document does not take account of the fact that the picture will be divided into regular blocks forming a kind of checker board pattern.